Molecular-level control of nitrogen sites enables CO2 electro-reduction under industrially relevant conditions

Abstract Industrial flue gases typically contain only 3–15% CO 2 , and direct electrochemical reduction on such dilute feeds would eliminate costly upstream purification. However, mass transport limitations and competing hydrogen evolution severely restrict activity under these CO 2 -starved conditions, and the governing molecular factors remain poorly understood. Here, we demonstrate that pyridinic-nitrogen enrichment in Ni–N–C single-atom catalysts enables efficient CO 2 reduction under dilute CO 2 . By tuning the pyridinic-N to pyrrolic-N ratio in well-defined Ni–N x sites, we probe the role of local nitrogen environments in CO 2 reduction rather than the metal center alone. Electronic-state analysis and density functional theory reveal that pyridinic-N forms a reversible CO 2 adduct that enhances local CO 2 accessibility near the active Ni center through a desorption–re-adsorption relay. These findings provide molecular-level insight by identifying a neighboring motif that regulates local CO 2 availability without perturbing the intrinsic Ni–N reaction pathway, and by establishing a transferable design principle for CO 2 reduction catalysts under CO 2 -limited conditions.